1. Field of the Invention
This invention generally relates to an image recording apparatus, and in particular to such an image recording apparatus including a photosensitive drum on which an image is formed by a light beam emitted from an optical writing device as modulated by an image information signal, such as a laser printer.
2. Description of the Prior Art
In an image recording apparatus, such as a laser printer or a facsimile machine, the emission of light is controlled by an image information signal or a laser beam is modulated by an image information signal to effect optical writing of an image on a photosensitive drum through an optical writing unit, so that an electrostatic latent image is formed on the drum. And the thus formed electrostatic latent image is then developed to form a visible, toner image which in turn is transferred onto a sheet of transfer paper by means of an image transfer corona unit. Then, the transferred toner image is permanently fixed onto the sheet of transfer paper as it moves through an image fixing unit.
In this type of an image recording apparatus, the optical writing unit is typically disposed above the photosensitive drum within a machine housing so that optical writing is typically effected at the top portion of the photosensitive drum. In addition, the image transfer corona unit is typically disposed below the photosensitive drum. Thus, an electrostatic latent image formed on the photosensitive drum at its top portion by the optical writing unit is developed to define a toner image which is then transferred onto a sheet of transfer paper, which is being transported with its imaging surface facing upward, at the bottom of the photosensitive drum.
With the above-described structure of a typical prior art image recording apparatus, when a paper supply unit was disposed side-by-side with a developing unit as projecting sideways or below the image transfer corona unit, there was provided a sufficient space for allowing a sheet of transfer paper to make an U turn without difficulty, which tended to make the entire structure larger in size. Besides, when a sheet of transfer paper happened to jam at the image transfer station or along a paper transportation path, it was necessary to set open the entire photosensitive drum unit including the optical writing unit, developing unit and photosensitive drum to remove the jammed sheet of transfer paper, which was a disadvantage from the operational viewpoint.